Will the alternator charge my second battery with a dual battery set-up???

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

They are 100 bucks a piece too. Rip off

Hi 2007jchill and the $100 is not the only rip off.

Their video demonstration of how their alleged “Alternator booster FUSE” catches on fire is a con job as well.

Their alleged “Alternator booster FUSE” is actually a commercially marketed diode specifically designed for use as a SPIKE SUPPRESSOR for DC motors.

This diode is supplied by a very large and reputable auto electrical parts distributor in the USA and sells for around $1.50.

Hard to consider this $1.50 "DIODE" is the same as their $100 priced device their deliberately misleading ad video is trying to make out is a cheap and "DANGEROUS" competitor for!

A perfect example of false and misleading advertising.

[Ian Reid Advanced Member Find all posts View Profile Close Ian Reid]

Didnt even realise there was an issue with charging voltage on the Prado. Just bought a camper trailer with two bateries and a dual batery kit for the Prado. Looks like i better order one of the gizmos too

[getaway ray Junior Member Find all posts View Profile Close getaway ray]

The best way to run dual batteries is with a Redarc BCDC to charge your aux battery.

[fido666 Banned Find all posts View Profile Close fido666]

The best way to run dual batteries is with a Redarc BCDC to charge your aux battery.

That's a bold statement, qualify please.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

The best way to run dual batteries is with a Redarc BCDC to charge your aux battery.

That's one way, whether its the best is up for debate, if it was that simple we wouldn't have countless threads debating this issue over and over again.

Personally I don't have DCDC or BCDC charger and mine works just fine thank you very much.

Cheers Andrew

[getaway ray Junior Member Find all posts View Profile Close getaway ray]

I used to work for Telstra and we would never attempt to charge dissimilar batteries with different charging requirements. the Redarc BCDC isolates the Aux batt from the alternator and charges it like a battery charger would. This gives maximum life to Aux batt. The alternator is only designed to put in enough to start car not fully charge battery which BCDC does.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Hmmm, sounds good but in the real world:

The following data extracted from a Prado with booster diode fitted:

Peak charge current 61.6A

Average recharge current first hour 28.1A

Average recharge current for last 40 minutes 14.68A

Total charge put back in in 1 hour 40 minutes in the first hour 42.78A (85.5%)

A 20A DCDC charger would have replaced 33.33A in the same time. (66.66%)

Battery fully charged in around 2 hours.

DCDC charger only put back in around 75% in the same time.

Don't believe all you read in the glossies.

As for the rest, the Redarc will recharge all AGM's at a maximum charge voltage of 14.5V, A CTEK 14.4V. A standard alternator will recharge at 14.4V at the same ambient, a booster alternator around 14.4V - 14.4V so much for the alternator will not fully charge a battery, if it can't then the DCDC charger can't either.

By the way, battery chargers were designed as a substitute generator/alternator, they use the same charge voltages that alternators and generators have for the past 100 years or so!

Leigh

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

I used to work for Telstra and we would never attempt to charge dissimilar batteries with different charging requirements. the Redarc BCDC isolates the Aux batt from the alternator and charges it like a battery charger would. This gives maximum life to Aux batt. The alternator is only designed to put in enough to start car not fully charge battery which BCDC does.

Yeah all that's correct, but as Leigh said in the real world things are a bit different. Not sure how you powered your BCDC in the Telstra situation but I imagine it was running for very long periods of time, unlike discharging a second battery when travelling and you may only have an hour or 2 to of running time to recharge the battery.

If you have long charging times and your aim is to get maximum battery life then maybe its the way to go. If you have limited or irregular charging periods and your aim is to keep the fridge cold then its not necessarily the "best" or the fastest way, but it certainly is one way.

I've been charging dissimilar batteries with just the alternator for years, my current second battery is going on 5 years old and still holds a charge nicely, and I often run a fridge and a freezer off it when travelling.

Cheers Andrew

[D4D Addicted PP Member Find all posts View Profile Close D4D]

The best way to run dual batteries is with a Redarc BCDC to charge your aux battery.

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

I used to work for Telstra and we would never attempt to charge dissimilar batteries with different charging requirements. the Redarc BCDC isolates the Aux batt from the alternator and charges it like a battery charger would. This gives maximum life to Aux batt. The alternator is only designed to put in enough to start car not fully charge battery which BCDC does.

Hi getaway Ray and I’m not sure if you are deliberately being somewhat disingenuous or you just don’t know the difference but the batteries Telstra and other operators of Remote Area Power Supplies ( RAPS ) use are nothing like automotive batteries so they do have to use the same type batteries.

Standby type batteries, which is what they use in Communication type RAPS setups, have a lower acid to water ratio than standard lead acid batteries and have to be charge in a different manor to standard lead acid batteries, but then again, thats probably why RAPS - Communication type lead acid batteries come with up to an 18 year life expectancy.

Don’t know of to many automotive batteries that come with an 18 year life expectancy.

There is absolutely no reason or advantage to be gained by separately charging different types of automotive lead acid batteries.

It’s nothing more than an advertising scare tactic and there are literally hundreds of thousands of DBS setups, made up of different types of batteries, all being charged by nothing more than the alternator, and no one has problems.

This means that there is no evidence to back your ( advertising ) theory.

[rob_macca67 Avid PP Poster! Find all posts View Profile Close rob_macca67]

Hey Leigh.....

I've just come back for the Cape where I struck troubles with my Alternator failing..... I've got an Aux Battery installed and for this trip I also had a 3rd battery (Optima battery) in the back of the car for the Fridge only. I've also got Toyota factory extended warranty and when I rang Toyota, they asked me if I had a dual battery.... when I said "yes", they then went on to say that I'm not covered due to the AUX Battery putting undue load/stress on the Alt and that I'm not covered..... Due to my location I wasn't in a position to argue, so I just got the local Auto-Elect to install and Aftermarket Alt and I plan to take the fight up with my local dealer when I get home..... With your knowledge, would having a 2nd Aux battery put undue stress/load on the Alternator causing premature failure?? I personally don't believe so, but thought I'd ask the question... The Auto Electrician said that the Pulley on the ALT is what failed and not the ALT itself. Apparently these ALTs are only supposed to turn one way and not the other where mine was free spooling in both directions so it appears the clutch setup on this Alternator has failed....

BTW: with the Alt troubles, I was very surprised at how quickly these model D4D engine's ran down the Main Battery volts when there was no charge input from the Alt. Within a couple of hours we had to stop and swap batteries with a mate and his car as the volts had dropped to around 11volts in about 2hrs (approx) of driving.....


Rob

Hmmm, sounds good but in the real world:

The following data extracted from a Prado with booster diode fitted:

Peak charge current 61.6A

Average recharge current first hour 28.1A

Average recharge current for last 40 minutes 14.68A

Total charge put back in in 1 hour 40 minutes in the first hour 42.78A (85.5%)

A 20A DCDC charger would have replaced 33.33A in the same time. (66.66%)

Battery fully charged in around 2 hours.

DCDC charger only put back in around 75% in the same time.

Don't believe all you read in the glossies.

As for the rest, the Redarc will recharge all AGM's at a maximum charge voltage of 14.5V, A CTEK 14.4V. A standard alternator will recharge at 14.4V at the same ambient, a booster alternator around 14.4V - 14.4V so much for the alternator will not fully charge a battery, if it can't then the DCDC charger can't either.

By the way, battery chargers were designed as a substitute generator/alternator, they use the same charge voltages that alternators and generators have for the past 100 years or so!

Leigh

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Hi Rob,

Depending on the batteries and how much current they will accept It is possible to overload the alternator with to many batteries. I have never seen this myself but can see how it could.

Generally though if you consider the cranking battery should be charged, connecting one discharge aux to the alternator should be no worse than starting the car with a flat cranking battery, starting the car with two flat aux's should be no worse than starting with a flat cranking battery and having a lot of the accessories turned on, ie aircon, rear window demister, head lights etc.

With three flat batteries, you would want to look at managing the load somewhat.

In your case it is really up to Toyota to prove the dual batteries caused the problem, I have read of the clutches failing on these alternators and believe this will become another issues as the KM's rise. The failures are probably due to wear and tear or dirt/water ingress etc, this is not alternator overload, it is a mechanical failure of the clutch.

I would ask the warranty mob to providing you with a written explanation on how they could determine over the phone your dual battery system would have caused a mechanical failure of the alternator clutch?

Cheers
Leigh

[Beach Advanced Member Find all posts View Profile Close Beach]

We're having this argument at work at the moment.

2010 150 GXL diesel. Dual battery, with a lot of equipment running off the 80ah aux battery via a 1000W inverter. I have just replaced the dead aux battery.

Due to the load we are placing on the aux battery, the vehicles charging system is not coping. I am not allowed to find a solution as we have an engineering/technical dept that knows all about this sort of thing. The trouble is they are divided.

One side says we need to install a DC-DC charger and eliminate the currently installed isolater switch between the batteries.
The other side is all for the booster diode method.
The DC-DC charger crowd say these things are unproven and not approved by Toyota or any other vehicle manufacturer.
The booster diode people retort by saying neither is any of the other stuff we have done to the vehicle, including adding a simple second battery set up.
DC-DC people: Evidence provided by booster diode suppliers is for recreational 4WD world. We are beyond that realm.
Boosters: The same applies to your mickey mouse charger.
DC-DC: Incorrect. These are used in all sorts of applications.
Boosters: You're all *%^$#@!
DC-DC: So are you. Twice.

Its very funny watching techy geeks fight.

In the meantime, I bought a CTEK charger and make sure the aux battery is on charge every time the vehicle is parked.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

A 1000W inverter, that's about 80 amps under full load, I don't who makes up your engineering section but I would get rid of them!

The Prado's charging system is not going to cope with that sort of load full time, I think from memory the alternator is rated at 100A, for continuous operation de-rate to at least 80% therefore you have 80 amps to play with, take off 30 amps for engine etc that leaves you with 50 amps at best, not hard to see what the problem is?

A booster diode or a DCDC charger can not make up for lack of amps to start with, you need a higher capacity alternator.

Also if running off the battery only, then the battery is not going to like that sort of discharge, you would want about four batteries to drop the load to around 20 amps a battery for a reasonable life if running the inverter near a 100% for long periods of time.

Cheers
Leigh

[Beach Advanced Member Find all posts View Profile Close Beach]

A 1000W inverter, that's about 80 amps under full load, I don't who makes up your engineering section but I would get rid of them!

The Prado's charging system is not going to cope with that sort of load full time, I think from memory the alternator is rated at 100A, for continuous operation de-rate to at least 80% therefore you have 80 amps to play with, take off 30 amps for engine etc that leaves you with 50 amps at best, not hard to see what the problem is?

A booster diode or a DCDC charger can not make up for lack of amps to start with, you need a higher capacity alternator.

Also if running off the battery only, then the battery is not going to like that sort of discharge, you would want about four batteries to drop the load to around 20 amps a battery for a reasonable life if running the inverter near a 100% for long periods of time.

Cheers
Leigh

Sorry I forgot to add in my previous post that I have stated many times to our "engineers" that we should be running all our main gear from an external generator. A Honda 1k would be fine and divide some of the gadget type devices to the aux battery if the desire is still there to stick with the dual battery system.

The problem there is the budget has already been spent and what would I know anyway?